Synthesis and antiviral activity of deoxy analogs of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) as potent and selective anti-HIV-1 agents

Several 6-benzyl analogs of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (1; HEPT) were synthesized and evaluated for their anti-HIV-1 activity. LDA (lithium diisopropylamide) lithiation of 5-ethyluracil derivatives 7 and 8 and subsequent reaction with an aryl aldehyde gave 6-(arylhydroxymethyl)-5-ethyluracil derivatives 9-12. 6-(Arylhydroxymethyl)-5-isopropyluracil derivatives 15-18 were prepared from the 5-isopropyl-2-thiouracil derivatives 13 and 14 by the above procedure following oxidative hydrolysis of the thione. Preparation of the target 5-alkyl-1-(alkoxymethyl)-6-benzyluracil derivatives 27-34 was carried out by acetylation of 9-14 followed by Pd-catalyzed hydrogenolysis. The 1-butyl- (37 and 39) and 1-(2-methoxyl)- (38 and 40) 5-alkyl-6-benzyluracils were synthesized by 1-alkylation of the 3-phenacyl derivatives 35 and 36 with alkyl halides followed by deprotection of the 3-phenacyl group. Compounds synthesized in this study inhibited HIV-1 replication in MT-4 cells in the submicromolar to namomolar concentration range. From this series of compounds, 6-benzyl-1-(ethoxymethyl)-5-isopropyluracil (33) was selected for clinical evaluation.